I am in the process of setting up a 90 gl reef tank. I found an excellent marine store, Marine Wharehouse in Tampa, that has been helpful. I am a little overwelmed on the lighting. Galaxy 150/175 watt MH Ballast with Reef Optix retro reflector and 2 175 watt 14K is the recommended lighting. I am concerned about the heat within the wood canopy and elsewhere without a chiller. It seems like the chiller is a must but then I am seeing T5's and compact florescent's that generate less heat. I am curious with the MH and a chiller how much the monthly energy is going to cost. The lighting is certainly confusing on what is the best option.
Otherwise, everything else is pretty simplified.

Nah.......you should be okay. I live in jacksonville....my lfs has a 150 halide on a 20 gallon......no heating issues at all. try it out....if it overheats add a fan. no biggie. and with a 90 gallon......I would certainly reccomend a 250 bulb. You want your light to reach the bottom and a 175 doesnt have enough umph to get there.